According to examination by the present inventors, in a recent semiconductor device manufacturing process, width of a pattern on a semiconductor is measured by a SEM (Scanning Electron Microscope) to control its process condition, and results of the measurement are fed back to process control parameters to control the process with high precision. This control is called APC (Advanced Process Control). As the pattern size of the semiconductor is reduced 100 nm order or less and a processing margin is smaller, not only a two-dimensional shape (shape viewed from right above) but also a three-dimensional shape of the pattern has to be measured and need to control the process with high precision is increased.
In contrast to this, Patent Document 1 (Japanese Patent Laid-Open Publication No. 2000-173984) discloses a technique of controlling an etching condition by combining an etching device and a sample surface evaluation system. Also, a device for measuring the three-dimensional shape of the sample include: a method called Scatterometry which measures an angle distribution or wavelength distribution of scattered lights to estimate the shape; a laser microscope which narrows a laser beam and do a scan to acquire height information from the brightness information of the detected beam; a confocal microscope which makes an illumination and detection through a pinhole to acquire height information from the brightness information of the detected light; and an interference microscope which detects a microscope image of an interference of a measurement beam and a reference beam to acquire height information from the brightness change information of the image.
There is also a method of an AFM (Atomic Force Microscope) which scans the surface by a minute probe with a very weak force. Or, there are methods of a stereo SEM which acquires depth information from a plurality of SEM images generated by varying the illumination direction of electron beams, a FIB-SEM which digs a cross-sectional surface by a FIB (Focused Ion Beam) to observe it from an oblique direction by a SEM, and an electron beam holography which re-construct a three-dimensional shape of a sample from a electron interference pattern.